Following my previous post, a few more things. As mentioned by Frédéric, it is – indeed – possible to compute the probability of all pairs. More precisely, all pairs are not as likely to occur: some teams can play against (almost) eveyone, while others cannot. From the previous table, it ... [Read more...]

MotivationI was inspired by Revolution's blog and step-by-step tutorial from Jeffrey Breen on the set up of a local virtual instance of Hadoop with R. However, this tutorial describes the implementation using VMware's application. One downside to using VMware is that it's not free. I know most of the people ... [Read more...]

I really enjoy reading the Junk Charts blog.  A recent post made me wonder how easy it would be to add summary curves for small-multiple type plots, assuming the “small multiples” to summarize were the X component of a ggplot2::facet_grid(Y ~ X) … Continue reading → [Read more...]

The recent releases of Rcpp 0.10.2 and RcppClassic 0.9.3 had one more repercussion. On that dreaded OS, the linker no longer wanted to instantiate a symbol present in both packages; seems to me that the linker in the other two OSs is a little smarter... [Read more...]

Much of my research in machine learning is aimed at small-sample, high-dimensional bioinformatics data sets. For instance, here is a paper of mine on the topic. A large number of papers proposing new machine-learning methods that target high-dimensional data use the same two data sets and consider few others. These ... [Read more...]

It is winter which makes it time for one of Netherlands beloved sports: speed skating. Speed skating is done over various distances, but for me, the most beautiful is the 10 km. The top men do this in about 13 minutes. In this post I try to u... [Read more...]

Buffon's needle problem is a question first posed in the 18th century by Georges-Louis Leclerc, Comte de Buffon:What is the probability that a needle thrown at a lined sheet of paper will cross a line?This problem can be used to estimate π. If we set the nail size and ... [Read more...]

We have seen the use of the STL transform functions in the posts STL transform and Transforming a matrix. We use the same logic in conjuction with a logical (ie boolean) vector in order subset an initial vector. #include using namespace... [Read more...]

data.table (http://datatable.r-forge.r-project.org/) inherits from data.frame and provides functionality in fast subset, fast grouping, and fast joins. In previous posts, it is shown that the shortest CPU time to aggregate a data.frame with 13,444 rows and 14 columns for 10 times is 0.236 seconds with summarize() in Hmisc ... [Read more...]

In the Visualizing Principal Components post, I looked at the Principal Components of the companies in the Dow Jones Industrial Average index over 2012. Today, I want to show how we can use Principal Components to create Clusters (i.e. form groups of similar companies based on their distance from each ... [Read more...]

Find Duplicate Files This is a simple script to search a directory tree for all files with duplicate content. It …Continue reading » [Read more...]

The package maptools includes new functions to label points and labels. Line labelling The lineLabel function produces and draws text …Continuar leyendo » [Read more...]

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The STL transform function can be used to pass a single function over a vector. Here we use a simple function square(). #include using namespace Rcpp; inline double square(double x) { return x*x ; } // [[Rcpp::export]] std::vector [Read more...]

Ok, I was supposed to take a break, but Frédéric, professor in Tours, came back to me this morning with a tickling question. He asked me what were the odds that the Champions League draw produces exactly the same pairings from the practice draw, and the official one (... [Read more...]

A reader’s comment on my ARMA Models for Trading post asked about different aspects of my experience with ARMA+GARCH for trading forecasting. The more I thought about it, the more it looked like a full post. So here we go. Starting with the high level – what packages did ... [Read more...]

After the work I did for my last post, I wanted to practice doing multiple classification.  I first thought of using the famous iris dataset, but felt that was a little boring.  Ideally, I wanted to look for a practice … Continue reading → [Read more...]

I’m going to continue with my ‘making data visually appealing to the masses’ kick. I happen to like graphics and graphing data. I also happen to like American football (For the record, however, I’m a soccer player first, a rugby … Continue reading → [Read more...]

Before heading home for the holidays, I had a large data set (1.6 GB with over 1.25 million rows) with columns of text and integers ripped out of the company (Kwelia) Database and put into a .csv file since I was going to be offline a lot over the break. I tried ... [Read more...]

In a 1995 interview Steve Jobs said he thought that computer programming should be a liberal art. In other words, he thought everyone’s education should include a year of learning a computer language, because it teaches you how to think in a certain way. If that was true in 1995, just ... [Read more...]